A lumbar support apparatus has a curved plate, which is provided to a seat-back frame so that an upper part of the curved plate is rotatable in a vertical direction and which is deformable in a direction along which a seated person's lumbar spine is pressed, a curved-plate deformation-amount adjustment unit, which moves a lower part of the curved plate in the vertical direction and adjusts a deformation amount of the curved plate relative to a seated person's back part, and a drive unit, which drives the curved-plate deformation-amount adjustment unit.
The curved-plate deformation-amount adjustment unit includes a wire, which is arranged to move in the vertical direction and to which the lower part of the curved plate is attached, and a drum, onto which both end portions of the wire are wound. When the drum is rotated, one wire-side is continuously unwound from the drum and the other wire-side is wound onto the drum, so that the wire is moved in the vertical direction and a deformation amount of the curved plate is thus adjusted (for example, refer to Patent Document 1).